Carrier-current telegraph system



Aug. 26, 1930 w. T. REA

CARRIER CURRENT TELEGRAPH SYSTEM Filed June 25. 1929 SEQ INVENTOR BY WEBem Ma s ATTO'RN EY a UNITED WILTON '1'. man, or rtusnm 'unw roux, Assxeuonro; J mam rELEPHQNIi AND1= a Patented Aug. 26, 1 930 1 Applicationfiled ni e '25,

' This invention ieiares a teleg p 'f tems and more particularly totelegraph sys If tems utilizing one or more' carrier channels telegraphmesv I Y amplifier-detector l3@ and the winding of; a? receiving relay14. Bridgedacross circuit 11 for the transmission of the sages.

: 7 One of theprimaryobjects ofthe invention consists in providing acarrier. telegraph system for interconnecting two terminals'and"iIl'WhiCh' system the carrier current for two the terminals Sucharrangements would be particularly desirable inthe' development of"short-haul systems, which might'inc'lude' as one of theterminals'thereof-a small office at f which the provision of a generatorof carrier way transmission issupplied at onlyone of currents might becommercially undesirable. Other-features and objects'ofthe inventionwill appear more fully from the detailed description thereof hereinaftergiven. i

I The invention may. be'inore 'fully understood from the followingdescriptiontogether with the accompanying drawing in 'the figureofwhich' is shown a circuit diagram embody.-' ing the invention. r l

'In the drawing is shown a half duplex carrier telegraph systeminterconnecting sta- 7 tion E1 and station W. This system com- I1'ngfs'1gnal3tothe loop 15. I station E to station W and line LEfortrans-ifi" e n w I e f closed, station "E ;may' send the carrierour?" rent; ,The carrier/current will "actuatethe 1 "receivinga'pparatusfat station but will i mmw overfthe 'line LE'sincefjcircuit l8prises the line LW 'for transmission from mission from station W tostation E; Re peater apparatus, suchas 8,19,22'and 23 may be included inthese lines. At station E, line LW is connected to a sending buscircuit7 to which may be connected a plurality ofsend-i 7 ing circuits fordiflerent carrier channels.

One of such circuits 4 isillustrated and will include a -filter 6 and ageneratorvfi for generating carrier frequency oscillations. Bridgedacross 'c1rcu1t4 1s a circuit 3 which,

when c losed will short-circuit the carrier oscillations from thegenerator 5. Circuit 3 of receiving circuits for various carrierchannels. vOne of suchcircuits is shown and includesa filter 25, anamplifier-detector26 and thewinding of a receiving relay 27. At stationW, the line LW is connected to a ceiving relay 14. at'the stationWisipoled in? '21 "and thencezto the'line'IZE 'circuited-when theloopvl5 isIc'l osed-L '7 The subscriber at either station :may sendreceiving bus circuit 10 to which m ay be fc onnectedi -a plulfality of-receiving circuits for isa circuit 17 which is'con'nected-to a-circuit-,18; The circuit. 18"is connected "through the 'filter 20 toasendingbus circuit 21 which insturn is: connected: to the line LE; j Circni't=18 maybe short-circuited bythe circuit l0 Which'isun'derthecontrolpfthe sending relay 16 the loop circuit; 15. 1

1 "When the loo circuits rand ,15 at both ends of thesystem' are closed,carrier current flows in the linefLWbut not in the linel JE. This isbecause the carriercurrent trans mitted over the'l'ine LW and thenceovercircuits 11; -17 and; 18 will'b'e short-'circu'ited' by I I circuit40. The receivingrelay '27 at the Jeastterminal 'is so poled that ittransmits a spacing signalfto the loop 1 when current is J flowingthrough its windingsanda marking t signal when no current isflowing. 1 The ref the usual way, namely,'the flow of current through its windings*will tran mit a inark is 'sh ort-"circuited by thejoperation 'ofcircuit 40"an'd'th'e sending relay {16l jWhen .theloop over line LW'willbe' transmitted over (sir- 1 'cuits'lilil? nd 18 to, thesending buseircuit f Theresi'stance 19; is" included in circuit 18 k to preventcircuit 40 fromicausing the input to the amplifier-detector 13omjbeingshort {f i Q I,

'ajbreak signal by' opening his .key; F In t he case of a breakbythfeisublsclriber atstation' Epthe key, ofrloopgcircuitwill beopenedili i fand'the output: of generator owill be shorts 1 circuited.Accordingly, carrier current will cease to flow over the line LW and thesubscriber at station W will receive a continuous spacing signal. Whenthe subscriber at statlon W opens the key of loop circuit to send, abreak signal, short-circuit will be removed from-circuit 18. Under theseconditions, when the subscriber at station E closes 7 his key, carriercurrent will flow over line 10 115W sac thence over circuits 11, 17, 1B,21

zoparting from the spirit of the invention as *defined by the appendedclaims. 3 What is claimed is:

:L A carriertelegraph system comprising twoterminals interconnected bytwo line see- ,au tions, each fortransmission in opposite directionsbetween said terminals, means at one of said terminals for applyingcarrier current to one of said line sections "for transmission toreceiving apparatus at the other of ao said terminals, and meansassociated with said receiving apparatus for applying a portion of thereceived carrier current to the other of said line sections fortransmission to receiving apparatus at the first of said ter-35.1ninals. V r

2. A carrier telegraph system comprising two stations, each of saidstations comprising telegraph sending and telegraph'receiving apparatus,two line sections interconnecting said stations, each for transmissioninopposit-e directions between said stations, means at one of saidstations under the control of the sending apparatus'thereat for applyingcarrier current to one of said line sections for transmisslon tothereceiving apparatus 7 at the other-of said, stat-ions, a means connectedto saidlast mentioned receiving apparatus for applying ,a'portion ofsaid reportion of said received carrier current to the other of saidline sections for transmission to the receiving apparatus at said firststation, a device in said circuit having an impedance similar to that ofthe receiving apparatus at the second station, and means at'said secondstation'controlled by the sending apparatus thereat for controlling saidcircuit.

4. A carrier telegraph'systemcomprising two stations, each of saidstations comprising telegraph sending and telegraphreceivingapparatus,'-the telegraph receiving apparatus at the firststation including a receiving relay so adjusted that when current flowsthrough its windings a spacing signal will be given, the telegraphreceiving apparatus at the second station including a receiving relay soadjusted that when current flows through its windings a marking signalwill be given, two line sections interconnecting saidstations, meansatthe first station'under control of the sending apparatus thereat forapplying carrier current'to one of said line sections'for transmissionto thereceiving apparatus at the second station, means connected to saidlast mentioned receiving apparatus for applying a portion of saidreceived carrier current to the other of said line sections fortransmission to the receiving apparatus at the first station, andmeansat said second station controlled by the sending apparatus'thereat forcontrolling said last mentioned means. r v

In testimony whereof, I havejsig'ned-my name to this specification this24th day of June, 1929. N I

WILTON T. 'REA.

eeived carrier current to the other of'said saline sections fortransmission to the receiving apparatus at said first station, and meansI at said second station controlled by the sendin'g apparatus thereatfor controlling said last mentioned means.

"3. A carrier telegraph systemcomprising two-stations, each of saidStiltiOllStOIIJPliS- ing telegraph sending and telegraph receiving aparatus, two line sections interconnecting sa t1 stations, means at oneof said stations undercnntrol of the sending apparatus thereat forfapplying' carrier cur'rent toone "tif'sai'dline sections fortransmissionto the receiving apparatns'atthe other of saidstatim'rs,a-cirtuit'connected'to said last menw' fleneu receiving apparatus for aplying a

